Question: Simplify the following expression: $k = \dfrac{5r - 25p}{15q + 5r} - \dfrac{25q + 20p}{15q + 5r}$ You can assume $p,q,r \neq 0$.
Explanation: Since the expressions have the same denominator we simply combine the numerators: $k = \dfrac{5r - 25p - (25q + 20p)}{15q + 5r}$ $k = \dfrac{5r - 45p - 25q}{15q + 5r}$ The numerator and denominator have a common factor of $5$, so we can simplify $k = \dfrac{r - 9p - 5q}{3q + r}$